Successive versions of a model

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Jean-Jacques Laublé
Junior Member
Posts: 12
Joined: Fri Mar 29, 2002 3:39 am

Successive versions of a model

Post by Jean-Jacques Laublé »

Hi Martin

This question is not only fundamental to SD modelling but to any method that
is systematic,

as long as the environment has not changed too much between the two
successive models.

I would be much interested to know if the first model had any influence on
the decisions taken and if after a period of time, on can evaluate if this
influence had any beneficial effect. If it had no beneficial effect, is it
possible to learn something from it, so as to be able to construct a second
model more efficient.

I have started many models that influenced more or less my decisions, but
having no method to revise them after a while and to measure the utility of
their influence, I have left them aside and they are now waiting an eventual
awakening in a problematic future.

In his book Sterman has just exposed the problem (page 20 and 34,35).

In another part of the Business Dynamic Sterman writes about replicability
page 855 and especially page 857 beginning of page about the few cases where
researchers build about the original work of their predecessors. It is
certainly because first the original work were not build to ease the
continuation of the research and that for some reasons, people lack a method
to evaluate what is good and bad in any study AFTER A PERIOD OF TIME, and
what to do to change it.

I am greatly interested to learn something about the subject.

Jean-Jacques Laublé
From: =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <
JEAN-JACQUES.LAUBLE@WANADOO.FR>
Allocar, Rent a Car
Strasbourg France
John Sterman
Senior Member
Posts: 117
Joined: Fri Mar 29, 2002 3:39 am

Successive versions of a model

Post by John Sterman »

Martin Schaffernicht is right on when he suggests that models are
always provisional and subject to change as conditions change. The
best and shortest statement on this principle is from 1970, when Jay
Forrester wrote a memo entitled "" 'The' Model Versus a Modeling
'Process' "", which was subsequently reprinted in the first issue of
the SD Review:

Forrester, J. W. (1985). ""'The' Model Versus a Modeling 'Process'.""
System Dynamics Review 1(1): 133-134.

John Sterman
From: John Sterman <jsterman@MIT.EDU>
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